Process for making bowling pins



Sept. 18, 1951 R. E. CLARK 2,568,274

m u m Patented Sept. 18, 1951 UNITED STATES PATENT OFFICE PROCESS FOR MAKING nowmNG PINS' Ray E. Clark, Willowbrook, Calif. Application October 8, 1948, Serial No. 53,553 3 Claims. (01. 18-59) This invention relates to a process for makin bowling pins.

Bowling pinsmade entirely of wood when subjected to the impacting action of bowling balls are caused to be forcibly thrown against the hard wood of the alleys. This battering of. the pins against the alleys soon results in the pins becoming nicked and gouged, especially at and around their bottom standing surface or base, thus making it difficult and often impossible to stand such worn pins upright on the alley surface. Worn pins due to such wear become unbalanced and are, therefore, obnoxious to bowlers. In addition, the bowling pins along the region of bowling ball impact in a comparatively short time of use show a marring or breaking away of the grain. surface, necessitating the renovation of the pins, namely, turning, then sanding, and finally painting. After the bowling pins have undergone several of such renovations they become so small in circumference as to fall through the pin setting machines, thereby being no longer usable.

An object of the present invention is to provide a process for making a wooden bowling pin having a band extending about the periphery of the pin at substantially the region of impact of a bowling ball therewith, the band being fabricated of impact resistant material.

Another object of the present invention is to provide a process of making a wooden bowling pin having a base and a band extending about the periphery of the pin at substantially the region of impact of a bowling ball therewith, the base and band being fabricated of impact resistant material.

A further object of the present invention is to provide a process of making a wooden bowling pin having a base and a band spaced from the base fabricated of impact resistant material which is simple in execution and highly eflicient.

Other objects and advantages of the invention will be apparent from the following description taken in conjunction with the accompanying drawing, wherein:

Figure 1 is a side elevational view of a typical bowling pin showing the undercutting of the base and the annular groove and communicating bores prior to the subjection of the pin to a molding operation with a moldable plastic material settable upon heating.

Figure 2 is a sectional view taken on 2-4 of Figure l.

Figure 3 is a sectional view taken on the line 3-3 of Figure 1.

Figure 4 is a side elevational sectionalview 01 the line a two part mold having the bowling pin of Figure I mounted therein, with the ejection mechanism containing a charge of the moldable plastic material settable upon heating in position to effect the injection stroke.

Figure 5 is a side elevational view, partly in section, of a bowling pin having the base and band of impact resistant material formed by the process of the present invention.

In carrying out the process of the present invention, a conventional type wooden bowling pin l0, Figures 1 and 2, is cut away inwardly from the periphery of the pin adjacent its bottom II to form a cutaway bottom section l2 of the desired area-for forming the base of impact resistant material. Formed in the periphery of the pin [0 at substantially the region of impact of a bowling ball therewith is an annular groove l3, the groove preferably tapering inwardly in cross section. Positioned along the longitudinal axis of the pin I0 is a bore [4, the bore extending from the bottom of the pin to the annularly grooved region of the pin ID. The annular groove I3 is interconnected with the longitudinal bore 14 by means of radial bores 15. Passageways l6 and I1 interconnect the cutaway section 12 with the longitudinal bore 10, the passageways extending from the cutaway section 12 upwardly and inwardly into the longitudinal bore l4. Thus, the first step in the process is forming the pin I0 witha cutaway bottom section, an annular groove extending about the periphery at substantially the region of impact of a bowling ball therewith, a bore positioned along the longitudinal axis and extending from the bottom of the pin to the annularly grooved region, a plurality of radial bores extending from the longitudinal bore and communicating with said groove, and passageways extending from the cutaway'section to and into the longitudinal bore. The pin 10 having its main body formed as herein above described is then placed in a two part forming mold I8, Figure 4, so designed as to form the desired base and band extending about the periphery of the pin at substantially the region of impact of a bowling ball therewith, both the base and band being fabricated of impact resistant material. The mold i8 is provided with an injection mechanism 19 for forcibly in jecting a liquid into such mold, the mechanism including a cylindrical container 20 for the reception of liquid material therein, a detachable cover 2| therefor, a nozzle 22 projecting into the interior of the mold l8 and in communication with thegcontainerZB, and a piston 23 slidably movable in the container 20 and supported in the cover 2|. The liquid employed in the container 20 is a moldable plastic material settable upon heating, which material after setting and an in- 4 a pressure of from 1000 to 8000 pounds per square inch; and for casein, the temperature should be increased to 200 to 225 degrees Fahrenheit with a pressure of from 2000 to 2500 pounds per square tegral part of a bowling pin has the inherent 5 inch. Preferably, a reinforcing material such as property of being impact resistant or resistant to cotton flock, shredded canvas, should be admixed the impact of a bowling ball with the bowling pin. with each of the aforementioned resins when em- The liquid moldable plastic material settable upon ployed for this purpose. heating may be non-cured rubber which has been Other materials that may be employed as the preheated to a temperature such as to render l moldable plastic material settable upon heating it molten or liquid, for example a temperature are thermoplastics such as cellulose acetate, celluof 270 to 280 degrees Fahrenheit. With the conlose butyrate, cellulose propionate, ethyl cellutainer 20 charged with a mass of molten nonlose, polyvinyl chloride, vinyl chloride acetate, cured rubber the piston 23 is caused to-be moved polyvinyl formal, polyvinyl butyral, polystyrene, downwardly, thereby causing the molten rubber l styrene elastomer, polyethylene, polyamide. For to flow through the longitudinal bore 'Ill into and" each of the foregoing the following range of out of the radial bores into the :annular groove molding temperature and range of pressure are l3, a portion of the molten rubber flowing through required.

Thermoplastic gg gg Pressure Cellulose Acetate. 340-500 3,000 to 30,000 lbs. per sq. inch.

Cellulose Butyrate 340-420 Do.

Cellulose Propionate. 300-500 D0.

Ethyl Cellulose 350-500 Do.

Polyvinyl Chloride 300-400 10,000 to 30,000 lbs. per sq. inch.

Vinyl Chloride Acetate Polyvinyl Formal.

18,000 to 30,000 lbs. per sq. inch. 10,000 to 30,000 lbs. per sq. inch.

Polyvinyl Butyral... 250-340 15,000 to 30,000 lbs. per sq. inch. Polystyrene 375-500 10,000 to 30,000 lbs. per sq. inch. Styrene Elastomer 355-410 15,000 to 20,000 lbs. per sq. inch. olyethylene 325-375 4,500 to 20,000 lbs. per sq. inch. Polyamide 510-600 5,000 to 50,000 lbs. per sq. inch.

the passageways t6 and I! into the space surrounding the cutaway section l2. When the longitudinal bore l4, radial bores l5, annular groove [3, passageways l6 and fl, and space. surrounding the cutaway section [2 have been completely filled with the molten rubber, the piston 23 is placed under increased pressure by any suitable means and the temperature of the molten rubber increaesd to the vulcanizing or curing temperature. Under these conditions of temperature and pressure the rubber is allowed to. set for a length of time depending upon the composition of the rubber. Preferably, the temperature is raised to a temperature of 290 to 300 degrees Fahrenheit and a pressure of 500 pounds per square inch. When the rubber has set, the temperature. and pressure are reduced to normal temperature and pressure, whereupon the bowling pin I 0 is. removed from the forming mold la, The resultant product is a completely formed bowling pin, Figure 5, having a base 25 and a band 26 extending about the periphery of the pin I0. at substantially the region of impact of a bowling ball therewith, both the base and band being fabricated of impact resistant material.

In place of employing non-cured rubber as the moldable plastic material settable upon heating, thermo setting resins like phenol formaldehyde, phenol furfural, urea formaldehyde, melamine formaldehyde, casein, may be used. Each of such resins would first have to be heated to a temperature to convert it to a molten state, and then the temperature would have to be increased to the setting temperature accompanied by the required application of pressure. For phenol formaldehyde and phenol furfural, the temperature should be increased to 270 to 400 degrees Fahrenheit with a pressure of from 2000 to 8000 pounds per square inch; for urea formaldehyde, the temperature should be increased to 290 to 325 degrees Fahrenheit with a pressure of from 1000 to 5000 pounds per square inch; for melamine formaldehyde, the temperature should be increased to 280 to 370 degrees Fahrenheit with What is claimed is:

v 1. In a process of making a, wooden bowling pin having a base and a band extending about the periphery of the pin at substantially the region of impact of a bowling ball therewith, the band being fabricated of impact resistant material, the steps comprising forming said pin with an annular groove extending about the periphery at substantially the region of impact of a bowling ball therewith, a cutaway bottom section extending longitudinally inwardly from the periphery of said pin adjacent to and terminating in the bottom of said pin, and a bore extending from the bottom of the pin and communicating with said groove and said section, filling said groove, the space surrounding said cutaway section and bore with a molten moldable plastic material settable upon heating, and subjecting said plastic material to an elevated temperature and pressure to form a band of impact resistant material attached to said pin.

2. In a process of making a wooden bowling pin having a base and a band extending about the periphery of the pin at substantially the region of impact of a bowling ball therewith, both the base and band being fabricated of impact resistant material, the steps of forming said pin with a cutaway bottom section extending longitudinally inwardly from the periphery of said pin adjacent to and terminating in the bottom of said pin, an annular groove extending about the periphery at substantially the region of impact of a bowling ball therewith, a bore positioned along the. longitudinal axis and extending from the bottom of the pin to the annularly grooved region, a plurality of radial bores extending from the longitudinal bore and communicating with said groove, and passageways extending from the cutaway section to and into the longitudinal bore, filling the groove, bores, passageways, and space'surrounding said cutaway section with a molten moldable plastic material settable upon heating, and subjecting said plastic material to an elevated temperature and pressure to form a base and band of impact resistant material attached to said pin.

3. In a process of making a wooden bowling pin having a base and a band extending about the periphery of the pin at substantially the region of impact of a bowling ball therewith, both the base and band being fabricated of impact resistant material, the steps of forming said pin with a cutaway bottom section extending longitudinally inwardly from the periphery of said pin adjacent to and terminating in the bottom of said pin, an annular groove tapering inwardly in cross section and extending about the periphery at substantially the region of impact of a bowling ball therewith, a bore positioned along the longitudinal axis and extending from the bottom of the pin to the annularly grooved region, a plurality of radial bores extending from the longitudinal bore and communicating with said groove, and passageways extending upwardly and inwardly from the cutaway section to and into the longitudinal bore, filling the groove, bores, passageways, and space surrounding said cutaway section with a molten moldable plastic material settable upon heating, and subjecting said plastic material to an elevated temperature and pressure to form a base and a band of impact resistant material attached to said pin.

RAY E. CLARK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

